Oligomer and polymer comprising triphenyl phosphine units

ABSTRACT

An oligomer or polymer comprising a first repeat unit and a second repeat unit that may be the same or different, the first repeat unit having formula (I): wherein each E independently represents optionally substituted nitrogen or optionally substituted phosphorus, with the proviso that at least one E is optionally substituted phosphorus; each Ar 1 , Ar 2  and Ar 3  is the same or different and independently represents an optionally substituted aryl or heteroaryl; n is 0-3; and in the case of unsubstituted nitrogen and phosphorus, the second repeat unit is directly conjugated to the first repeat unit.

FIELD OF THE INVENTION

This invention relates to semiconductive oligomers and polymers, theirsynthesis and use in optical devices.

BACKGROUND OF THE INVENTION

One class of opto-electrical devices is that using an organic materialfor light emission (an organic light emitting device or “OLED”) or asthe active component of a photocell or photodetector (a “photovoltaic”device). The basic structure of these devices is a semiconductingorganic layer sandwiched between a cathode for injecting or acceptingnegative charge carriers (electrons) and an anode for injecting oraccepting positive charge carriers (holes) into the organic layer.

In an organic electroluminescent device, electrons and holes areinjected into a layer of electroluminescent semiconducting materialwhere they combine to generate excitons that undergo radiative decay.Holes are injected from the anode into the a highest occupied molecularorbital (HOMO) of the electroluminescent material; electrons areinjected from the cathode into the lowest unoccupied molecular orbital(LUMO) of the electroluminescent material. An organic hole injectingmaterial is commonly provided to assist injection of charge from theanode into the electroluminescent layer. In WO 90/13148 the organiclight-emissive material is a conjugated polymer, namely poly(p-phenylenevinylene) (“PPV”). Other light emitting polymers known inthe art include polyfluorenes and polyphenylenes. In U.S. Pat. No.4,539,507 the organic light-emissive material is of the class known assmall molecule materials, such as (8-hydroxyquinoline) aluminium(“Alq₃”). Light emitting polymers such as polyfluorenes andpolyphenylenes are advantageous in that they are solution processable.In particular, solution processable light emitting polymers may beinkjet printed as described in EP 0880303 to produce high informationcontent displays, in particular full colour displays.

An essential requirement for an effective OLED is efficient injection ofholes and electrons into the electroluminescent layer of the OLED.Therefore, a focus in the OLED field is the development of hole and/orelectron transporting materials to be used in combination with theelectroluminescent material. An effective hole transporting Material hasa HOMO level that lies between the workfunction of the anode (or organichole injecting material) and the HOMO level of the electroluminescentmaterial.

Another focus in the OLED field is the development of full colour OLEDs,i.e. OLEDs comprising red, green and blue electroluminescent materials.A drawback of many blue organic electroluminescent materials is thattheir emission is a relatively pale blue, due to an insufficiently largeHOMO-LUMO bandgap, when compared to the standard blue as defined by 1931CIE co-ordinates. WO 99/48160 discloses hole transporting co-polymers“TFB” and “PFB”:

These materials may be used as hole transporting materials and/or asblue electroluminescent materials. However, the above identifiedco-polymers have drawbacks. In particular, the HOMO levels of thesematerials are not ideally matched to the workfunction of the typicalanode and/or organic hole injecting material, which negatively affectstheir hole transporting properties. Furthermore, the blue emission fromthese materials is a relatively pale blue.

There therefore exists a need for polymers having good hole transportingproperties and a deeper blue colour. Phosphine-containing polymers areknown. For example, EP 0339424 discloses polythioarylenes with phosphinerepeat units. Repeat units within this polymer are not conjugatedtogether, but are separated by a sulfur atom. These polymers aredescribed for use in fields taking advantage of their inert,thermoplastic properties and as such the teaching of this document isnot relevant to the field of the present invention of organicsemiconductors.

J. Organomet. Chem. 653, 167-176, 2002 discloses a homopolymercomprising a diphenyl-alkylphosphine repeat unit.

WO 99/32537 discloses polymers comprising repeat units each of whichconsists essentially of units Ar₃Y where Y can be N, P, etc. Copolymersof units Ar₃Y with other repeat units are not mentioned. In thepreferred embodiment of this application, Y represents nitrogen; thereare no embodiments wherein Y is phosphorus or any indication ofadvantages of phosphines over the exemplified amines. Furthermore, thereis no disclosure of how copolymers comprising such repeat units may besynthesised.

SUMMARY OF THE INVENTION

The present inventors have surprisingly found that usingtriarylphosphines in place of prior art triarylamines results insignificant improvement in hole transporting properties of the materialand deeper blue emission.

Accordingly, in a first aspect the invention provides an oligomer orpolymer comprising a first repeat unit and a second repeat unit that maybe the same or different, the first repeat unit having formula (I):

wherein each E independently represents optionally substituted nitrogenor optionally substituted phosphorus, with the proviso that at least oneE is optionally substituted phosphorus; each Ar¹, Ar² and Ar³ is thesame or different and independently represents an optionally substitutedC₃ to C₃₀ aryl or heteroaryl; n is 0-3; and in the case of unsubstitutednitrogen and phosphorus, the second repeat unit is directly conjugatedto the first repeat unit.

The triarylphosphines according to the invention are more stable thanthe diphenylalkyl phosphine described in the prior art because the lonepair of the phosphorus has an extra π-system to donate into. Incontrast, the alkyl group of the prior art diphenylalkylphosphinesdonates electron density to the phosphorus atom.

In one preferred embodiment, each of Ar¹, Ar² and Ar³ is an optionallysubstituted phenyl.

In another preferred embodiment, Ar² is optionally substituted biphenyl.More preferably, Ar¹ and Ar³ according to this embodiment are optionallysubstituted phenyl.

In a yet further preferred embodiment, Ar³ is optionally substitutedheteroaryl.

In one preferred embodiment, each E is phosphorus. In another preferredembodiment, n is 0 and E is phosphorus. In still another preferredembodiment, n is 1-3 and at least one E is nitrogen.

The electronic or physical properties of the oligomers or polymersaccording to the invention (such as, respectively, electron affinity orsolubility) may be modified by suitable substituents. Therefore, it ispreferred that, at least one Ar³ is substituted by a substituentselected from the group consisting of optionally substituted, branched,cyclic or linear C₁₋₂₀ alkyl or C₁₋₂₀ alkoxy; C₁₋₂₀ fluoroalkyl,fluorine, optionally substituted diarylamine and optionally substituteddiarylphosphine.

Where the group E is phosphorus, it may be trivalent or pentavalentphosphorus. Preferably, E is selected from the group consisting ofunsubstituted nitrogen, unsubstituted phosphorus or phosphorus oxide.

Preferably, the second repeat unit is different from the first repeatunit. More preferably, the second repeat unit is selected fromoptionally substituted phenyl, fluorene, spirobifluorene,indenofluorene, heteroaryl, dihydrophenanthrene or triarylamine.

In a second aspect the invention provides a method of forming anoligomer or polymer according to any preceding claim comprising the stepof oligomerising or polymerising a monomer of formula (II) in thepresence of a metal catalyst of variable oxidation state:

wherein Ar¹, Ar² and Ar³, E and n are as described-with respect to thefirst aspect of the invention, and each LG is the same or different andrepresents a leaving group capable of participating in apolycondensation mediated by a metal of variable oxidation state.

Preferably, the polycondensation comprises a metal insertion step with anickel or palladium complex catalyst.

Preferably, each LG is the same or different and is independentlyselected from halogen; a reactive boronic group selected from a boronicacid group, a boronic ester group and a borane group; or a moiety offormula —O—SO₂-Z wherein Z is selected from the group consisting ofoptionally substituted alkyl and aryl.

Alternative groups LG include a group of formula -(DZ)_(m)-B-Hal₃ ⁻M⁺wherein DZ represents a diazonium group, each Hal independentlyrepresents a halogen and M⁺ represents a metal cation; and a group offormula O—SiR⁷ ₃ wherein each R⁷ independently represents an optionallysubstituted alkyl or aryl.

Preferably, Hal is fluorine. Preferably, M⁺ is an alkali metal morepreferably sodium or potassium. Preferably, R⁷ is alkyl more preferablymethyl.

In a first preferred embodiment of the second aspect, each LG isindependently a halogen or a moiety of formula —O—SO₂-Z, and the monomerof formula (II) is oligomerised or polymerised in the presence of anickel complex catalyst.

In a second preferred embodiment of the second aspect, the monomer offormula (II) is oligomerised or polymerised with a second aromaticmonomer in the presence of a palladium complex catalyst and a base and

-   -   a. each LG is the same or different and comprises a reactive        boronic group and the second monomer comprises two reactive        groups independently selected from halogen and a moiety of        formula —O—SO₂-Z, or    -   b. each LG independently comprises a halogen or a moiety of        formula —O—SO₂-Z and the second monomer comprises two reactive        boron groups which are the same or different.

In a third preferred embodiment of the second aspect, one LG is areactive boron group; the other LG is a halogen or a moiety of formula—O—SO₂-Z; and the monomer of formula (II) is oligomerised or polymerisedin the presence of a palladium complex catalyst and a base.

In a third aspect, the invention provides a monomer comprising a repeatunit of formula (III):

wherein Ar¹, Ar² and Ar³, E, LG and n are as defined in any one ofclaims 1-5; each R¹ independently represents hydrogen or optionallysubstituted, branched, cyclic or linear C₁₋₂₀ alkyl, aryl or heteroaryl;and both groups OR¹ associated with the same boron atom may be joined toform a ring.

Preferably, LG has a formula —B(OR¹)₂

Preferably, at least one R¹ represents a linear, branched or cyclicC₁₋₂₀ alkyl.

Preferably, the at least one group —B(OR¹)₂ represents an optionallysubstituted residue of formula (IV):

Preferably, at least one carbon atom of the residue of formula (IV) issubstituted. More preferably, both carbon atoms are substituted.Preferred substituents are linear, branched or cyclic C₁₋₂₀ alkyl. Mostpreferably, each carbon carries two methyl groups (pinacol ester).

In a fourth aspect, the invention provides an optical device comprisingan oligomer or polymer according to the first aspect of the invention.

Preferably, the oligomer or polymer is located in a layer between afirst electrode for injection of holes and a second electrode forinjection of electrons.

Preferably, the optical device is an electroluminescent device, i.e. adevice that produces electroluminescence from the oligomer or polymerwhen a forward bias is applied across the electrodes. Alternatively, thedevice may be a photovoltaic device.

In a fifth aspect, the invention provides a switching device comprisingan oligomer or polymer according to the first aspect of the invention.

Preferably, the switching device is a field effect transistor comprisingan insulator having a first side and a second side; a gate electrodelocated on the first side of the insulator; an oligomer or polymeraccording to the first aspect of the invention located on the secondside of the insulator; and a drain electrode and a source electrodelocated on the oligomer or polymer.

In a sixth aspect, the invention provides an integrated circuitcomprising a field effect transistor according to the fifth aspect ofthe invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention is described hereinafter with reference to polymers andpolymerisation, however it will be appreciated that this descriptionapplies equally to corresponding oligomers and oligomerisation.

Polymers according to the invention may be used as active materials inany of the aforementioned optical devices, in particularelectroluminescent devices and photovoltaic devices (i.e. photodetectorsor photocells) or in switching devices such as field effect transistors.

When used in OLEDs, polymers according to the invention may be used assolution processable, electron transporting, hole transporting and/oremissive materials in organic light emitting devices.

Examples of repeat units according to the invention include thefollowing:

In light of the invention, it will be appreciated that polymerscomprising phosphine-containing repeat units are analogous totriarylamine repeat units wherein N-atoms have been replaced by P-atoms,and as such may be used in a manner analogous to prior arttriarylamines. In particular, polymers comprising repeat units accordingto the invention may be used as hole-transporting or blue emissivematerials.

The repeat unit may comprise a plurality of P-atoms in place of N-atomsas in repeat units e, g, h, i, j and l above. Alternatively, only one orsome of the N-atoms may be replaced by a P-atom or P-atoms as per unit for k above. The aryl groups of each repeat unit may optionally besubstituted (units a, c, and e-j) or unsubstituted (units b, d, k andl). The valency of phosphorus in each repeat unit may be trivalent(units a-c, e-h, j-l), pentavalent (unit d) or a mixture of both (uniti).

The repeat units above represent only some of the possible substituentsand substitution patterns for repeat units on the invention. Each of theabove repeat units may also be unsubstituted or substituted with one ormore substituents X in a manner analogous to that described below fortriarylamines.

Examples of substituents X include solubilising groups such as C₁₋₂₀alkyl, perfluoroalkyl or alkoxy; electron withdrawing groups such asfluorine, nitro or cyano; and substituents for increasing glasstransition temperature (Tg) of the polymer such as bulky groups, e.g.tert-butyl or optionally substituted C₃ to C₃₀ aryl or heteroarylgroups. Also substituents representing a combination of the above, suchas C₆ to C₃₀ alkylaryl or arylalkyl groups, are possible. The polymersmay be prepared by Suzuki polymerisation as described in, for example,WO 00/53656 or WO 03/048225 and Yamamoto polymerisation as described in,for example, T. Yamamoto, “Electrically Conducting And Thermally Stableπ-Conjugated Polyarylenes Prepared by Organometallic Processes”,Progress in Polymer Science 1993, 17, 1153-1205, or WO 04/022626. Forexample, in the synthesis of a linear polymer by Yamamotopolymerisation, a monomer having two reactive halide groups is used.Similarly, according to the method of Suzuki polymerisation, at leastone reactive group is a reactive boron group.

Suzuki polymerisation employs a Pd(0) complex or a Pd(II) salt.Preferred Pd(0) complexes are those bearing at least one phosphineligand such as Pd(Ph₃P)₄. Another preferred phosphine ligand istris(ortho-tolyl)phosphine, i.e. Pd(o-Tol)₃. The usual ratio of Pd:phosphine ligand lies in the range of 1:1 to 1:10. However, in thepresent case the phosphine monomer according to formula (III) could alsoact as a ligand for Pd. In view of this, it is surprising that Suzukipolymerisation for the production of the inventive polymer works verywell, even though the Pd: phosphine ratio is much higher due to thepresence of the phosphine-based momomers of formula (III). PreferredPd(II) salts include palladium acetate, i.e. Pd(OAc)₂. Suzukipolymerisation is performed in the presence of a base, for examplesodium carbonate, potassium phosphate or an organic base such astetraethylammonium carbonate.

Yamamoto polymerisation employs a Ni(0) complex, for examplebis(1,5-cyclooctadienyl)nickel(0).

Suzuki polymerisation may be used to prepare regioregular, block andrandom copolymers from aromatic monomers with two leaving groups LG. Adescription how polymers with blocky structures can be synthesised isdescribed in detail for example in DE 10337077.3. In particular,homopolymers or random copolymers may be prepared when one leaving groupLG is a halogen and the other leaving group LG is a reactive borongroup. Alternatively, block or regioregular, in particular AB copolymersmay be prepared when both leaving groups of a first monomer are boronand both leaving groups of a second monomer are halide.

The monomer according to the invention may be polymerised alone to forma homopolymer or in the presence of one or more co-monomers to form aco-polymer. Possible co-repeat units derived from such co-monomers areoutlined below; it will be appreciated that each of these co-repeatunits may be derived from a comonomer comprising two polymerisablegroups independently selected from halogen (preferably chlorine, bromineor iodine, more preferably bromine), a boronic acid group, a boronicester group and a borane group.

As alternatives to halogens as described above, leaving groups offormula —O—SO₂Z can be used wherein Z is as defined above. Particularexamples of such leaving groups are tosylate, mesylate and triflate.

Numerous other combinations of leaving groups LG for the two monomersused in Suzuki polymerisation will be apparent to the skilled person.These include:

boronic acids or esters with trialkylsiloxy groups;

boronic acids or esters with diazonium tetrafluoroborates (TetrahedronLetters, 1997, Vol 38, No 25, pp 4393-4396);

diazonium tetrafluoroborates with metal trifluoroborates (TetrahedronLetters, 1997, Vol 38, No 25, pp 4393-4396); and

metal trifluoroborates with aryi halides using ligand free palldium(e.g. palladium acetate) (Organic Letters, 2002, Vol 4, No 11, pp1867-1870).

Where the polymer according to the invention is a co-polymer, it maypossess the repeat unit of the invention with one or more differentco-repeat units. In a copolymer, the repeat unit of the invention ispreferably present in the polymer in 1 to 50 mol%, more preferred in 5to 30 mol%. One class of co-repeat units is arylene repeat units, inparticular: 1,4-phenylene repeat units as disclosed in J. Appl. Phys.1996, 79, 934; fluorene repeat units as disclosed in EP 0842208,trans-indenofluorene repeat units as disclosed in, for example,Macromolecules 2000, 33(6), 2016-2020; cis-indenofluorene repeat unitsas described in EP 03014042.0; spirobifluorene repeat units as disclosedin, for example, EP 0707020; dihydrophenanthrene repeat units asdisclosed in DE 10337346.2 and stilbene repeat units (commonly known as“OPV” repeat units) as disclosed in WO 03/020790. Each of these repeatunits is optionally substituted. Examples of substituents includesolubilising groups such as C₁₋₂₀ alkyl or alkoxy; electron withdrawinggroups such as fluorine, nitro or cyano; and substituents for increasingglass transition temperature (Tg) of the polymer such as bulky groups,e.g. tert-butyl or optionally substituted C₃ to C₃₀ aryl groups.

A further class of preferred co-repeat units are repeat units comprisingone or two amino groups in the repeat unit backbone such as co-repeatunits comprising triarylamine groups, in particular repeat units offormulae 1-3:

wherein X in each occurrence is independently hydrogen or a substituentand m is 1-3. Preferably at least one X is independently selected fromthe group consisting of C₁ to C₂₀ alky, aryl, perfluoroalkyl, thioalkyl,cyano, alkoxy, heteroaryl, alkylaryl and arylalkyl groups. Particularlypreferred groups X are C₁ to C₁₀ n-alkyl (in particular n-butyl),branched C₁, to C₁₀ alkyl (in particular s-butyl and t-butyl), an C₁, toC₁₀ n-alkoxy or a trifluoroalkyl (in particular trifluoromethyl) groupbecause they are suitable for helping to select the HOMO level and/orfor improving solubility of the polymer. Preferably, m is 1 or 2, morepreferably 1. Preferably, where X is a substituent it is located in themeta- or para-position, most preferably in the para-position.

Use of trifluoromethyl groups in repeat units of this type is disclosedin WO 01/66618.

A yet further class of co-repeat units include heteroaryl repeat unitssuch as optionally substituted 2,5-thienyl, pyridyl, diazine, triazine,azole, diazole, triazole, oxazole or oxadiazole; or optionallysubstituted units of formulae 4-10:

wherein each Y represents sulfur or oxygen, preferably sulfur; and R⁵and R⁶ are the same or different and are each independently hydrogen ora substituent group. Preferably, one or more of R⁵ or R⁶ may be selectedfrom hydrogen, C₁ to C₂₀ alkyl, aryl, perfluoroalkyl, thioalkyl, cyano,alkoxy, heteroaryl, alkylaryl, or arylalkyl. Most preferably, R⁵ and R⁶are independently hydrogen, C₁ to C₁₀ alkyl or phenyl. Preferably, forpractical reasons, R⁵ and R⁶ are the same when both are a substituent.

When used in an OLED, polymers according to the invention possess atleast one of hole transporting, electron transporting and emissiveproperties. Where the polymer has more than one of these properties,different properties may be provided by different monomer repeat unitsor segments of a block co-polymer, in particular segments of the polymerbackbone as described in WO 00/55927 or pendant groups as described inWO 02/26859. Alternatively, if the polymer of the invention has only oneor two of the properties of hole transport, electron transport andemission, it may be blended with one or more further polymers having theremaining required property or properties as described in WO 99/48160.

Optical devices tend to be sensitive to moisture and oxygen.Accordingly, the substrate of the device preferably has good barrierproperties for prevention of ingress of moisture and oxygen into thedevice. The substrate is commonly glass, however alternative substratesmay be used, in particular where flexibility of the device is desirable.For example, the substrate may comprise a plastic as in U.S. Pat. No.6,268,695 which discloses a substrate of alternating plastic and barrierlayers or a laminate of thin glass and plastic as disclosed in EP0949850.

Although not essential, the presence of a layer of organic holeinjection material over the anode is desirable as it assists holeinjection from the anode into the layer or layers of semiconductingpolymer. Examples of organic hole injection materials include PEDT/PSSas disclosed in EP 0901176 and EP 0947123, or polyaniline as disclosedin U.S. Pat. No. 5,723,873 and U.S. Pat. No. 5,798,170.

The cathode is selected in order that electrons are efficiently injectedinto the device and as such may comprise a single conductive materialsuch as a layer of aluminium. Alternatively, it may comprise a pluralityof metals, for example a bilayer of calcium and aluminium as disclosedin WO 98/10621, or a thin layer of dielectric material such as lithiumfluoride to assist electron injection as disclosed in, for example, WO00/48258.

The device is preferably encapsulated with an encapsulant to preventingress of moisture and oxygen. Suitable encapsulants include a sheet ofglass, films having suitable barrier properties such as alternatingstacks of polymer and dielectric as disclosed in, for example, WO01/81649 or an airtight container as disclosed in, for example, WO01/19142.

In a practical optoelectronic device, at least one of the electrodes issemi-transparent in order that light may be absorbed (in the case of aphotoresponsive device) or emitted (in the case of a PLED). Where theanode is transparent, it typically comprises indium tin oxide. Examplesof transparent cathodes are disclosed in, for example, GB 2348316. Wherethe polymer of the invention is used in a switching device such as afield effect transistor, it will be appreciated that all of theelectrodes may be opaque.

The PLED may be a static image device, i.e. a device that displays onlya single image. In the simplest case, the device comprises an anode,cathode and electroluminescent polymer, each of which are unpatterned.Such a device may be suitable for lighting applications or signsdisplaying a fixed image. Alternatively, the device may be a variableimage device, i.e. a device wherein different areas of theelectroluminescent layer may be independently addressed. Such a devicemay be a segmented, passive matrix or active matrix device.

The polymer may be deposited by any one of a range of techniques such asspin-coating, dip-coating, inkjet printing as disclosed in EP 0880303,laser transfer as described in EP 0851714, flexographic printing, screenprinting and doctor blade coating. If the technique requires depositionof the polymer from solution, then any one of a range of organicsolvents or mixtures of organic solvents may be used including, forexample, alkyl-aromatics, in particular mono- or poly-alkylbenzenes suchas toluene, xylene and durene.

The present inventors have identified numerous advantages of thepolymers according to the invention as compared to prior artamine-containing polymers, as follows:

The polymers according to the invention have a significantly largerHOMO-LUMO bandgap (Eg) than comparative polymer not containing repeatingunits according to formula (I) (compare Table 1 below). Furthermore, thepolymers according to the invention have bluer 1931 PAL CIE co-ordinatesfor both photoluminescence (PL) and electroluminescence (EL) (compareTable 2 below).

In addition, the present inventors have found that a small red peak isobserved in the electroluminescent spectrum of several amine-containingpolymers. In contrast, this peak is absent in the electroluminescentspectra of polymers according to the invention.

Other advantages of the phosphines according to the invention over priorart amines are higher external quantum efficiency and current ca. 2.5times higher for polymers according to the invention.

Although the present invention has been described in terms of specificexemplary embodiments, it will be appreciated that variousmodifications, alterations and/or combinations of features disclosedherein will be apparent to those skilled in the art without departingfrom the spirit and scope of the invention as set forth in the followingclaims.

EXAMPLES Monomer 1: P,P-bis(4-bromo-3,6-dimethylphenyl)phenylphosphine

n-Butyllithium (151.5 mmol, 61 ml, 2.5 M solution in hexanes) was addedto a solution of 2,5-dibromo-p-xylene (40 g, 151.5 mmol, 1 equiv.) indry tetrahydrofuran (500 ml) at −78° C. After the addition was finishedthe reaction was left to stir for 30 minutes.P,P-dichloro-phenylphosphine (10.3 ml, 75.8 mmol, 0.5 equiv.) was thenadded slowly taking care to keep the temperature below −75°C. A deep redcolouration was observed on addition of the phosphine. After theaddition was complete the reaction was allowed to warm up to roomtemperature overnight. The THF was then removed under reduced pressureand the resulting solids taken up in dry toluene. This product/saltmixture was then filtered through a silica plug (toluene eluent, 1 l)and reduced to give a white solid (GC-MS purity approximately 98 %). Thecrude solid was crystallised from either ethylacetate/methanol or hexaneto give the above product (30.5 g, yield 85%). GC-MS 99.8 %, M⁺ 476(expected M⁺ 476); 31P-NMR (CDC13) δ (ppm) 198.

Monomer 2: P,P-bis(4-bromo-3,6-dimethylphenyl)phenylphosphine oxide

Monomer 1 (30 g, 63.0 mmol, 1 equiv.) was dissolved in methylene choride(200 ml) at room temperature m-Chloroperoxybenzoic acid (MCPBA, 50 wt%,ca. 22 g, 63.0 mmol, 1 equiv) was then added portion wise. A smallexotherm was noted. Once the addition was complete, thin layerchromatography revealed complete conversion after approximately 5minutes. The crude product was extracted with aqueous sodium hydroxide(2 M) and the organic layer evaporated under reduced pressure to givethe crude product as a white solid. Crystallisation from ethanol gavethe title compound (19 g, 63%). GC-MS 99.6%, M⁺ 491 (expected M⁺ 491));31P-NMR (CDCl3) δ (ppm) 34.

Polymer synthesis

Polymer 1

A copolymer of 6,6,12,12-tetra(n-octyl)trans-indenofluorene-2,8-diyl(T8IF) and the repeat unit derived from Monomer 1 in a ratio of 85%T8IF: 15% phosphine (Polymer 1) was formed by Suzuki polymerisationaccording to the method set forth in WO 00/53656 using monomer 1 (15mol%), the ethylene glycol ester of6,6,12,12-tetra(n-octyl)indenofluorene-2,8-diboronic acid (T8IF-B, 50mol %) and 2,8-dibromo-6,6,12,12-tetra(n-octyl)indenofluorene (T8-IF-Br,35 mol %).

Polymer 2

Polymer 2 was formed by following the procedure for Polymer 1 aboveexcept that Monomer 2 was used in place of Monomer 1.

Device Examples

Electroluminescent devices 1 and 2 were made using polymers 1 and 2respectively. The devices were formed by providing a glass substratecarrying an anode of indium tin oxide and onto this (a) depositing byspin-coating a layer of poly(ethylene dioxythiophene)/poly(styrenesulfonate) available from H. C. Starck as Baytron P; (b) depositing byspin-coating from xylene solution a layer of polymer according to theinvention and (c) depositing by vacuum evaporation a cathode comprisinga first layer of calcium and a second, capping layer of aluminium. Thedevice was sealed using an airtight container available from SaesGetters SpA.

The HOMO and LUMO level of the material according to the invention wasmeasured by cyclic voltammetry. For the purpose of comparison, PolymerC1 was made according to the process described above for Polymer P1except that Monomer C1 (below) was used in place of Monomer 1.

Monomer C1

As can be seen from Table 1 below, the polymers according to theinvention have a significantly larger HOMO-LUMO bandgap (Eg) thancomparative polymer C1. Furthermore, Table 2 shows that the polymersaccording to the invention have bluer 1931 PAL CIE co-ordinates for bothphotoluminescence (PL) and electroluminescence (EL).

In addition, the present inventors have found that a small red peak isobserved in the electroluminescent spectrum of amine-containing polymerssuch as Polymer C1. In contrast, this peak is absent in theelectroluminescent spectra of both polymers 1 and 2. TABLE 1 PolymerHOMO LUMO Eg 1 5.538 2.288 3.25 (electrical) 2 5.587 2.299 3.288(electrical) C1 4.991 2.299 2.692 (electrical)

TABLE 2 Polymer EL CIEx, y PL CIEx, y 1 0.161, 0.079 0.149, 0.173 C10.165, 0.124 0.150, 0.180

Other advantages of the phosphines according to the invention over priorart amines, as observed between Polymer 1 and Polymer C1, are higherexternal quantum efficiency (2.06% vs. 1.34%) and current ca. 2.5 timeshigher for Polymer 1.

Although the present invention has been described in terms of specificexemplary embodiments, it will be appreciated that variousmodifications, alterations and/or combinations of features disclosedherein will be apparent to those skilled in the art without departingfrom the spirit and scope of the invention as set forth in the followingclaims.

1-23. (canceled)
 24. An oligomer or polymer comprising a first repeatunit and a second repeat unit that may be the same or different from thefirst repeat unit, the first repeat unit having formula (I):

wherein each E independently represents optionally substituted nitrogenor optionally substituted phosphorus, with the proviso that at least oneE is optionally substituted phosphorus; each Ar¹, Ar² and Ar³ is thesame or different and independently represents an optionally substitutedaryl or heteroaryl; n is an integer from 0 to 3; and if E is anunsubstituted nitrogen or unsubstituted phosphorus, then the secondrepeat unit is directly conjugated to the first repeat unit.
 25. Anoligomer or polymer according to claim 1 wherein each Ar¹, Ar² and Ar³is an optionally substituted phenyl.
 26. An oligomer or polymeraccording to claim 1, wherein at least one Ar³ is substituted by asubstituent selected from the group consisting of optionallysubstituted, branched, cyclic or linear C₁₋₂₀ alkyl or C₁₋₂₀ alkoxy;C₁₋₂₀ fluoroalkyl, fluorine, optionally substituted diarylamine andoptionally substituted diarylphosphine.
 27. An oligomer or polymeraccording to claim 1, wherein E is selected from the group consisting ofnitrogen, unsubstituted phosphorus and phosphorus oxide.
 28. An oligomeror polymer according to claim 1, wherein the second repeat unit isdifferent from the first repeat unit.
 29. An oligomer or polymeraccording to claim 1, wherein said oligomer or polymer comprises threeor more different repeat units.
 30. An oligomer or polymer according toclaim 29, wherein the second repeat unit and optionally further repeatunits are selected from optionally substituted phenyl, fluorene,spirobifluorene, indenofluorene, heteroaryl, dihydrophenanthrene and/ortriarylamine.
 31. A method of forming an oligomer or polymer comprisinga first repeat unit and a second repeat unit that may be the same ordifferent from the first repeat unit, the first repeat unit havingformula (I):

wherein each E independently represents optionally substituted nitrogenor optionally substituted phosphorus, with the proviso that at least oneE is optionally substituted phosphorus; each Ar¹, Ar² and Ar³ is thesame or different and independently represents an optionally substitutedaryl or heteroaryl; n is an integer from 0 to 3; and if E is anunsubstituted nitrogen or unsubstituted phosphorus, then the secondrepeat unit is directly conjugated to the first repeat unit; said methodcomprising: the step of oligomerising or polymerising a monomer offormula (II) in the presence of a metal catalyst of variable oxidationstate:

 wherein each LG is the same or different and represents a leaving groupcapable of participating in a polycondensation mediated by a metal ofvariable oxidation state.
 32. A method according to claim 31, whereineach LG is the same or different and is independently selected fromhalogen; a reactive boronic group selected from a boronic acid group, aboronic ester group and a borane group; or a moiety of formula —O—SO₂-Z,wherein Z is selected from the group consisting of optionallysubstituted alkyl and aryl.
 33. A method according to claim 32, whereineach LG is independently a halogen or a moiety of formula —O—SO₂-Z, andthe monomer of formula (II) is oligomerised or polymerised in thepresence of a nickel complex catalyst.
 34. A method according to claim32, wherein the monomer of formula (II) is oligomerised or polymerisedwith a second aromatic monomer in the presence of a palladium complexcatalyst and a base; and further wherein each LG is the same ordifferent and comprises a reactive boronic group and the second monomercomprises two reactive groups independently selected from halogen and amoiety of formula —O—SO₂-Z, or each LG independently comprises a halogenor a moiety of formula —O—SO₂-Z and the second monomer comprises tworeactive boron groups which are the same or different.
 35. A methodaccording to claim 32, wherein one LG is a reactive boron group; theother LG is a halogen or a moiety of formula —O—SO₂-Z; and the monomerof formula (II) is oligomerised or polymerised in the presence of apalladium complex catalyst and a base.
 36. A monomer comprising a repeatunit of formula (III):

wherein each E independently represents optionally substituted nitrogenor optionally substituted phosphorus, with the proviso that at least oneE is optionally substituted phosphorus; each Ar¹, Ar² and Ar³ is thesame or different and independently represents an optionally substitutedaryl or heteroaryl; n is an integer from 0 to 3; each LG is the same ordifferent and represents a leaving group capable of participating in apolycondensation mediated by a metal of variable oxidation state; andeach R¹ independently represents hydrogen or optionally substituted,branched, cyclic or linear C₁₋₂₀ alkyl, aryl or heteroaryl; and bothgroups R¹ associated with the same boron atom may be joined to form aring.
 37. A monomer as defined in claim 36, wherein LG has a formula—B(OR¹)₂.
 38. A monomer according to claim 36, wherein at least one R¹represents a linear, branched or cyclic C₁₋₂₀ alkyl.
 39. A monomeraccording to claim 37, wherein the at least one group —B(OR¹)₂represents an optionally substituted residue of formula (IV):


40. A monomer according to claim 39, wherein at least one carbon atom ofthe residue of formula (IV) is substituted.
 41. An optical devicecomprising an oligomer or polymer according to claim
 24. 42. An opticaldevice according to claim 41, wherein the oligomer or polymer is locatedin a layer between a first electrode for injection of holes and a secondelectrode for injection of electrons.
 43. An optical device according toclaim 42, wherein the device is an electroluminescent device.
 44. Aswitching device comprising an oligomer or polymer according to claim24.
 45. A field effect transistor, comprising: an insulator having afirst side and a second side; a gate electrode located on the first sideof the insulator; an oligomer or polymer according to claim 24, locatedon the second side of the insulator; and a drain electrode and a sourceelectrode located on the oligomer or polymer.
 46. An integrated circuitcomprising a field effect transistor according to claim 45.